Chemical agents can induce cancers by causing mutations in genes that control important checkpoints of cell division. The immune system has evolved to counter these mutations by recognizing mutated proteins and eliminating the cells that carry them. These mutated "self" proteins can serve as antigenic targets for the action of T lymphocytes. One of the fundamental problems in chemical carcinogenesis is that these mutations may not elicit the required T cell response, thereby leading to uncontrolled growth of some cancers. In this proposal, T lymphocytes will be "engineered" against such cancers. The approach will use a BALB/c mouse model of T cell therapy against a chemical-induced tumor called CMS5. CMS5 expresses a mutated MAP kinase with a single mutation (Lys to Gin) in a peptide that binds to the class I MHC molecule Kd. This peptide/MHC (tErk1/Kd) acted as the antigen recognized by the T cell clone C18. The T cell receptor (TCR) from clone C18 has been expressed previously in transgenic mice. The goal of the present work is to engineer mutants of the C18 TCR with higher affinity for tErk1/Kd and to express the high-affinity TCRs in T cells. My hypothesis is that T cells expressing higher-affinity TCRs will be more effective in the elimination of chemical-induced carcinomas. The specific aims are to: 1) generate TCRs that bind with high-affinity to the chemically induced tumor antigen tErk1/Kd, using in vitro engineering; 2) transfect in vitro engineered TCR genes into T cells and assess their sensitivity to the chemically induced tumor and to specific peptide variants; 3) investigate the in vivo anti-tumor response of adoptively transferred T cells bearing high-affinity TCRs against the chemically induced tumor.